FAP and head and neck squamous cell carcinoma: Figure 2A presents the results from 481 tumor samples pooled across the various tumor subtypes. The presence of FAP+ tumor stroma correlated positively with an increased density of CD3+ T cells and FoxP3+ cells which is characteristic of regulatory T cells, as well as proliferating and cytotoxic CD8+ cells. When the analyses were split by individual tumor indications, this correlation was most pronounced in RCC and NSCLC for most of these immune cell markers, while other tumors such as HNSCC and Breast cancer (BC) did not exhibit this significant correlation (Figure 2B).